Auxis

Frigate and bullet tunas Temporal range: Pliocene - Recent PreЄ Є O S D C P T J K Pg N
Bullet tuna, Auxis rochei
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Perciformes
Family:	Scombridae
Tribe:	Thunnini
Genus:	Auxis Cuvier, 1829
Species
See text.

Auxis is a genus of ocean-dwelling ray-finned bony fish in the family Scombridae, and tribe Thunnini, also known as the tunas. Auxis, commonly and collectively called the frigate tunas, is one of five genera of tunas which comprise the Thunnini tribe.

Species

There are two species in the genus Auxis, each with two subspecies.:^[1]

• A. rochei (Risso, 1810) (bullet tuna); marusōda (マルソウダ)
  • ssp.. A. rochei rochei (Risso, 1810), distributed tropic and subtropic oceans worldwide (Atlantic, Indian and Pacific: including the Mediterranean Sea.).^[2]
  • ssp. A. rochei eudorax Collette et Aadland, 1996, Eastern Pacific.^[2]
• A. thazard (Lacepède, 1800) (frigate tuna); hirasōda (ヒラソウダ)
  • ssp. A. thazard thazard (Lacepède, 1800), distributed tropic and subtropic Atlantic, Indian and Pacific Oceans.^[2]
  • ssp. A. thazard brachydorax Collette et Aadland, 1996, Eastern Pacific.^[2]

Description

Auxis can reach a length of 50–65 millimetres (2.0–2.6 in). They have a strong, fusiform body with a sharpened head. The teeth are small and conical. The two dorsal fins are separated by a wide gap. The pectoral fins are short. They have a dark, blue-black back, the top of the head may be deep purple or almost black. The belly is whitish and without streaks or spots.

Distribution

These fishes are widespread in all tropical and subtropical seas and oceans, and both mentioned species are present in the Mediterranean Sea with their subspecies (A. thazard thazard and A. rochei rochei).

Food

In Japan the two species in the genus are collectively called sōdagatsuo (Japanese: ソウダガツオ,宗太鰹), and this is also the common genus name. In Japanese cuisine, these fish are processed into sōdabushi, a product much like katsuobushi, though not really used in fine-dining restaurants or as condiment, but as a fish stock ingredient at more budget type popular-dining places, e.g., soba noodle shops.

Although fresh fish might be eaten as sashimi or grilled, it has a lot of dark-red meat (chiai), so it is valued much less than the similar katsuo (skipjack tuna). And it degrades quickly so shipment out to market is limited. The frigate tuna (hirasoda) is considered superior between the two.

Fossil record

Fossil of Auxis propterigius from Monte Bolca

Fossils of Auxis have been found in the Pliocene of Italy and United States (age range: from 5.3 to 3.6 million years ago.). ^[3]

References

1. Froese, Rainer, and Daniel Pauly, eds. (2012). Species of Auxis in FishBase. April 2012 version.
2. Collette, B.B. and C.R. Aadland 1996, Pacific. Fish. Bull. 94:423-441(Fishbase Ref. 32349)
3. Paleobiology Database

External links

• Froese, Rainer, and Daniel Pauly, eds. (2006). Species of Auxis in FishBase. January 2006 version.
• MNHN